Electrical resistor



Nov. 29, 1960 o. D. WATLEY 2,962,682

ELECTRICAL RESISTOR Filed Nov. 3, 1958 2 Sheets-Sheet 1 Jnvem'oz Orlin "Wat 129 b rm' dlfl'ortlg NOV. 29, 1960 4 O wATLEY 2,962,682

ELECTRICAL RESISTOR Filed NOV. 3, 1958 2 Sheets-Sheet 2 ,Jmjen IOt" @flin "D' Wallgy Wilyzss W ELECTRICAL RESISTOR Orlin D. Watley, Columbus, Nebr., assignor to Dale Products Incorporated, Columbus, Nebr.

Filed Nov. 3', 1958, Ser. No. 771,369

10 6 Claims. (Cl. 338-483) This invention relates to an electrical resistor sometimes known as a potentiometer or trimmer.

The use of resistors in various electrical circuits is old. Such resistors were of various types but the most common employed a coil of resistance wire. With the advent of highly complex electrical instruments and machines, resistors became a most important part of the electrical hook up, and often the failure of the apparatus was caused by the malfunctioning of the resistor or resistors. One reason for this was that the resistor was subject to pollution by water, dust collecting and like. A further objection was the absence of adjustment which in my device was most desirable and essential. A still further objection to the ordinary resistor was that it did not lend itself to printed circuits.

Therefore one of the principal objects of my invention is. to provide an adjustable sealed electrical resistor or trimmer.

A further object of my invention is to provide an electrical resistor that may be easily secured to an electrical printed circuit.

A still further object of my invention is to provide an electrical resistor that is easily and quickly assembled or repaired.

A still further object of this invention is to provide an adjustable resistor that provides more efiicient electrical contact between its moving parts.

' A still further object of this invention is to provide an electrical resistor that is economical in manufacture and durable in use.

These. and other objects will be apparent to those skilled in the art.

My invention consists in the construction, arrangements, and combination, of the various parts of the device, whereby the objects contemplated are attained as hereinafter more fully set forth, specifically pointed out in my claims, and illustrated in the accompanying drawings, in which:

Fig. 1 is a perspective view of my electrical resistor ready for installation;

Fig. 2 is an enlarged longitudinal sectional view of my device taken on line 22 of Fig. 1 and more fully illustrates its construction;

Fig. 3 is an enlarged cross sectional view of the resistor taken on line 3-3 of Fig. 2;

Fig. 4 is an enlarged cross sectional view of the device taken on line 4-4 of Fig. 2;

Fig. 5 is a perspective view illustrating the manner in which my electrical resistor is secured to a printed circuit;

Fig. 6 is an enlarged longitudinal sectional view of the resistor; and

Fig. 7 is an enlarged top plan view of a modified form of construction with sections cut away to illustrate its arrangement of parts.

In these, figures I have used the numeral 10 to designate the rectangular housing of the resistor and which is made of any suitable non-conductive material such as plastic.

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This housing has an opening in its top which is normally sealed by a detachable cover plate 11. This cover plate 11 may be of metal or plastic.

The cylindrical core of the rheostat or current carrying element is designated by the numeral 12. Around this core 12 is the usual rheostat metallic wire coil 13 as shown in Fig. 2. This rheostat extends lengthwise of the interior of the housing 10 and a circular depression 15 is provided in the bottom of the housing for the nesting of the rheostat as shown in Fig. 4. At the time the housing is formed, two bendable wire current carrying rods 16 and 17 are molded to extend through the bottom of the housing 10 and into the interior of the housing. These two lead wires 16 and 17 are electrically connected to the two ends of the rheostat respectively as shown in Fig. 6. At one side of the rheostat and in the bottom of the housing 10 I have provided an elongated current carrying metallic plate 18. This elongated plate extends parallel to the rheostat. At the same time that the lead wires 16 and 17 were molded to extend through the bottom of the housing 10 a third current carrying bendable wire 19 was molded through the bottom of the housing 10 as shown in Fig. 4. This lead wire 19 is electrically connected to the plate 18. The numeral 20 designates an elongated rotatably mounted rod having raised spiral threads 21. This rod 20 is mounted for rotation in spaced relationship above plate 18 and is parallel with the rheostat. One end of the rod .20 is reduced for rotation in the end wall of the housing as shown in Fig. 2.

The numeral 22. designates a hole in one end of the housing 10 and in alignment with the other end of the rod 20. The end of the rod 2 0 that extends into this hole opening 22 has a reduced knurled end 23 and which is imbedded in a plastic roller 25.. This roller 25 is rotatably mounted in the hole bore 22. Connected to the roller 25 and extending outwardly beyond the hole bore 22 is an adjustable screw head 26. This screw head 26 has its inner portion also rotatably mounted in the hole bore 22 and has a reduced portion carrying an 0- ring 27 of resilient material. Thus when the housing 10 is sealed the inner parts of my resistor will be successfully shielded from dust and other objectionable foreign matter. By rotating the screw head 26 which extends beyond the housing 10, the threaded rod 20 will be accordingly rotated. The numeral 28 designates the metallic contact element or wiper arm having a depression 29 in one end slidably contacting the wire coil 13 of the rheostat. The other end of the contact element extends downwardly and laterally under the threaded rod 20 to frictionally engage the plate 18 and then is curved upwardly and over the'threaded rod 20 as shown in Fig. 4. This curved portiqn of, the contact element has one or more angular groups 30 for contacting and engaging the spiral thread 21 of the rod 20. The contact member 28 is so bent that it is in constant frictional pressure both on the plate 18. and the coil wire of the rheostat. Obviously by rotating the screw head 26 in either direction the threaded rod 20 will be rotated and the contact element 28 will be. accordingly moved forwardly or backwardly across the wire coil 13 ofthe rheostat for purposes of adjustment. The numeral 31 designates a compression resilient spring plate at each end of the threaded rod for limiting its longitudinal sliding movement in both directions. Therefore it can readily be seen that my device is not only successfully sealed but highly accurate. In many instances a plurality of my devices will be needed and which are grouped in small areas. I have provided holes 32 through the end walls of the housing 10 whereby a number of my resistors may be secured and clamped together by any suitable means such as bolts or like.

I have used the numeral 35 to designate a sheet member having a printed circuit 36 with the usual eyelet openings 37 as shown in Fig. 5. In mounting my resistor I extend the contact lead wires 16, 17 and 19 through these eyelets. These lead Wires may be bent for securing my device to the printed circuit or if desired their surplus lengths may be cut off and the remaining portion soldered or otherwise secured to the printed circuit by solder or like.

In Fig. 7 I show a modified form of structure. The only difference, however, is that the connecting lead wires which I have designated 16', 17' and 19 instead of sticking through the bottom of the housing extend through the end of the housing. When this structure is used the device is used in a vertical position on the printed circuit instead of horizontally as shown in Fig. 5.

Some changes may be made in the construction and arrangement of my electrical resistor without departing from the real spirit and purpose of my invention, and it is my intention to cover by my claims, any modified forms of structure or use of mechanical equivalents which may be reasonably included within their scope.

I claim:

1. In a variable resistor, a housing of non-conducting material having a bore in one of its ends, an elongated coil wire rheostat in said housing, two lead wires each having one end connected to said rheostat and its other end extending from said housing, an elongated electroconductive plate in said housing and positioned in parallel spaced relationship to said rheostat, a threaded metallic rod in said housing rotatably mounted in spaced relationship to said elongated plate and having one of its ends in alignment with said bore, a lead wire connected to said elongated plate and extending from said housing, a rotatable member extending into said bore and operatively connected to said threaded rod, and a resilient electricityconducting wiper arm having a free end slidably frictionally engaging said rheostat, a central portion frictionally slidably engaging said plate and a free end portion rotatably engaging the threads of said threaded rod; said wiper arm extending first from said rheostat, thence to a position below said threaded rod, thence to said plate, and making electro-contact with the same, and thence over and around said threaded rod and making electro-contact with the same whereby the portion of said wiper arm engaging said plate will make electrical contact therewith and by such engagement with said plate will hold its portion that is engaging said rheostat in yielding engagement with said rheostat; said threaded rod and said plate providing l a dual electric current path.

2. In a variable resistor, a housing of non-conducting material having a bore in one of its ends, an elongated coil wire rheostat in said housing, two lead wires each having one end connected to said rheostat and its other end extending from said housing, an elongated electroconductive plate in said housing and positioned in parallel spaced relationship to said rheostat, a threaded metallic rod in said housing rotatably mounted in spaced relationship to said elongated plate and having one of its ends in alignment with said bore, a lead wire connected to said elongated plate and extending from said housing, a rotatable member extending into said bore and operatively connected to said threaded rod, and a resilient electricityconducting wiper arm having a free end slidably frictionally engaging said rheostat, a central portion frictionally slidably engaging said plate and a free end portion rotatably engaging the threads of said threaded rod; said wiper arm being of spring metal and extending first from said rheostat, thence to a position below said threaded rod, thence to said plate and making electrocontact with the same and thence over and around said threaded rod and making electro-contact with the same whereby the portion of said wiper arm engaging said plate will make electrical contact therewith and by such engagement with said plate will hold its portion that is engaging said rheostat in yielding engagement with said rheostat; said threaded rod and said plate providing a dual electric current path.

3. In a variable resistor, a housing of non-conducting material having a bore in one of its ends, an elongated coil wire rheostat in said housing; said housing having a curved inside bottom portion partially embracing said rheostat, two lead wires each having one end connected to said rheostat and its other end extending from said housing, an elongated electro-conductive plate in said housing and positioned in parallel spaced relationship to said rheostat, a threaded metallic rod in said housing rotatably mounted in spaced relationship to said elongated plate and having one of its ends in alignment with said bore, a lead wire connected to said elongated plate and extending from said housing, a rotatable member extending into said bore and operatively connected to said threaded rod, and a resilient electricity-conducting wiper arm having a free end slidably frictionally engaging said rheostat, a central portion frictionally slidably engaging said plate and a free end portion rotatably engaging the threads of said threaded rod whereby the portion of said wiper arm engaging said plate will make electrical contact therewith and by such engagement with said plate will hold its portion that is engaging said rheostat in yielding engagement with said rheostat; said threaded rod and said plate providing a dual electric current path.

4. In a variable resistor, a housing of non-conducting material having a bore in one of its ends, an elongated coil wire rheostat in said housing, two lead wires each having one end connected to said rheostat and its other end extending from said housing, an elongated electroconductive plate in said housing and positioned in parallel spaced relationship to said rheostat, a threaded metallic rod in said housing rotatably mounted in spaced relationship to said elongated plate and having one of its ends in alignment with said bore, a lead wire connected to said elongated plate and extending from said housing, a rotatable member extending into said bore and operatively connected to said threaded rod, a resilient electricityconducting wiper arm having a free end slidably frictionally engaging said rheostat, a central portion frictionally slidably engaging said plate and a free end portion rotatably engaging the threads of said threaded rod whereby the portion of said wiper arm engaging said plate will make electrical contact therewith and by such engagement with said plate will hold its portion that is engaging said rheostat in yielding engagement with said rheostat; said housing having an access opening, and a lid detachably enclosing said access opening; said threaded rod and said plate providing a dual electric current path.

5. In a variable resistor, a housing of non-conducting material having a bore in one of its ends, an elongated coil wire rheostat in said housing, two lead wires each having one end connected to said rheostat and its other end extending from said housing, an elongated electroconductive plate in said housing and positioned in parallel spaced relationship to said rheostat, a threaded metallic rod in said housing rotatably mounted in spaced relationship to said elongated plate and having one of its ends in alignment with and rotatably extending into said bore, a lead wire connected to said elongated plate and extending from said housing, a rotatable member extending into said bore and operatively connected to said threaded rod, and a resilient electricity-conducting wiper arm having a free end slidably frictionally engaging said rheostat, a portion frictionally slidably engaging said plate and a portion rotatably engaging the threads of said threaded rod; said wiper arm being bent whereby the portion of said wiper arm engaging said plate will make electrical contact therewith and by such engagement with said plate will hold its portion that is engaging said rheostat in yielding engagement with said rheostat; said threaded rod and plate providing a dual electric current path.

6. In a variable resistor, a molded housing of nonconducting material having a bore in one of its ends, an elongated coil wire rheostat in said housing, two lead wires each having one end connected to said rheostat and its other end extending from said housing, an elongated electro-conductive plate in said housing and positioned in parallel spaced relationship to said rheostat, a threaded rod in said housing rotatably mounted in spaced relationship to said elongated plate and having one of its ends in alignment with said bore, a lead wire connected to said elongated plate and extending from said housing, a metallic rotatable member extending into said bore and operatively connected to said threaded rod, and a resilient electricityconducting wiper arm having a free end slidably frictionally engaging said rheostat, a portion frictionally slidably 15 engaging said plate and a portion rotatably engaging the threads of said threaded rod; said plate also acting as a stop limitation holding said wiper arm in yielding frictional engagement with said rheostat; said threaded rod and plate providing a dual electric current path.

References Cited in the file of this patent UNITED STATES PATENTS 1,757,110 Chapman May 6, 1930 2,777,839 Thias Jan. 8, 1957 2,860,216 Hubbard et a1 Nov. 11, 1958 2,870,302 Bourns et al. Ian. 20, 1959 2,895,116 Morrison July 14, 1959 FOREIGN PATENTS 759,398 Great Britain Oct. 17, 1956 

